The present invention refers to an electrically operated dispensing appliance, in which said electric drive acts either upon at least one thrust rod for a storage cylinder via a driving screw or upon at least one piston rod cooperating with a feed cylinder.
In dispensing appliances, whether they are manually, pneumatically, or electrically operated, there is a risk that when the thrust rod and thus the feed piston is advanced in the storage cylinder, the latter is forced apart more or less according to the material, so that when the drive is stopped and the forward pressure is discontinued, the tension of the cartridge is released and the substance contained therein keeps flowing out.
On this background, it is a first object of the present invention to provide an efficient discharge of the electric advance in order to prevent any afterflow. Another object which is specific to electrically operated dispensing appliances is to manufacture the corresponding electric drive as simply and economically as possible while still being reliable. These objects are attained by an electrically operated dispensing appliance, wherein the electric drive comprises two electric motors, one of the electric motors acting upon the driving screw in order to rotate it in the advancing direction, and the other one of the electric motors acting upon the driving screw in order to retract it for a cartridge tension discharge, and in order to turn it back when the thrust rod(s) are retracted in order to exchange the storage cylinders.